OVERVIEW: Utility helpers for image upload, geo conversions, and response construction used across NAM backend.

WHERE TO LOOK
- utils/helper/image_uploader.go
  - Image uploaders: SaveDeviceImagesBulk, SaveTowerImagesBulk
  - Image upload constants: MaxFileSize (5MB), TowerUploadDir, DeviceUploadDir
- utils/helper/geo_helpers.go
  - Geo helper functions: ConvertToDeviceResponse, ConvertToOLTResponse, etc.
- utils/helper/response_builder.go
  - Centralized response builders used by delivery layer
- Additional helper files under utils/helper/ as needed for conversions and validators

CONVENTIONS
- File naming follows snake_case; exported functions use PascalCase.
- Constants use CamelCase with explicit units (MaxFileSize int64 = 5*1024*1024).
- Upload directories are defined as constants (TowerUploadDir, DeviceUploadDir) and used across helpers.
- Errors propagate with context; use standard errors or fmt.Errorf wrappers.
- Tests should cover public helpers; avoid testing private internals directly.

ANTI-PATTERNS
- Do not hardcode absolute system paths; rely on defined constants for directories.
- Do not bloat helper files with business logic; keep them pure and focused.
- Do not create global mutable state in helpers.
- Do not introduce circular imports between helper and delivery layers.
- Do not bypass validation for uploads; enforce MaxFileSize and allowed MIME types.